The present invention relates to a method according to the preamble of the main claim. The invention further relates to an system for carrying out the method referred to above in accordance with the preamble of the appropriate independent claim.
As is known, many methods exist for disinfesting the most varied types of products, food products or otherwise, by using appropriate gases, in particular CO2 and N2, argon or toxic gases.
All methods presently known operate under variable pressure conditions, such as in vacuo, under atmospheric pressure or under superatmospheric pressure; depending on the various operating conditions, various types of apparatus with various degrees of complexity and cost are employed to implement these methods. The use of one of the abovementioned known methods depends, in particular, on the product to be treated.
As an example of the above, we now consider the disinfestation of a manufactured wooden article infested with woodworm or of plant products, such as medicinal herbs and the like, compressed in their containers. Since, in the case of the manufactured wooden article, the woodworm bores channels within the ligneous structure, and in the case of compressed plant products the infesting agent may be present in holes within the body of the product, in order to ensure that the insect comes into contact with the disinfesting gas it is possible, according to a first method, to introduce the manufactured article into an atmosphere containing the disinfesting gas and wait until the latter penetrates to the interior of the channel by diffusion or, if the gas used has a specific gravity substantially greater than that of air, by gravity.
This known operating method is relatively simple and gives rise to restricted costs; however, it also presents various not inconsiderable disadvantages, included among which are the excessively long treatment times and the impossibility of completely replacing the ambient air within the channels or holes with disinfesting gas. In this context, for example, we may consider a channel which is formed vertically, where the open end is at the bottom: in this case, it is virtually impossible for a disinfesting gas which is heavier than air, such as for example CO2 or argon, to fill the channel completely and eliminate the infesting agent in whatever position it may be located. Consequently, the infesting agent survives where it does not come into contact with the disinfesting gas.
This known method, then, is of limited efficacy although it is carried out with a system using apparatus of limited cost.
In order to eliminate the disadvantages of the known method of disinfesting products, as described above, other methods are known as alternatives to that described previously.
One of these methods comprises carrying out the disinfestation by first creating, in a container in which the product under treatment is placed, first a high vacuum and then a partial vacuum obtained by breaking the high vacuum with the disinfesting gas. This is performed in the same container (or cell) in which the product is placed, this container being produced in a manner capable of resisting the vacuum throughout the period necessary to complete the disinfestation.
According to another known method, by contrast, disinfestation is carried out by placing the product in an appropriate cell, into which disinfesting gas (usually CO2) is introduced, for a predetermined period, under a pressure greater than atmospheric pressure.
With both of these last two known methods, the disinfesting gas or vapour penetrates into all the cavities of the manufactured article to be treated, thus permitting effective disinfestation. However, these methods are carried out using systems of very high cost, particularly in view of the mechanical performance required of the apparatus involved (in the former case, cells capable of maintaining the vacuum for some days; in the latter, cells under an operating pressure of, customarily, 20 bar).
An object of the present invention is to provide a method of disinfesting a product and an appropriate system for its implementation which make it possible to overcome the disadvantages of the known equivalent methods and systems.
In particular, it is an object of the invention to provide a method of the stated type which permits efficacious disinfestation of the products and, at the same time, offers more limited costs of implementation than those of the equivalent previously known methods.
Another object is to provide a system for the implementation of the abovementioned method which entails lower costs and is less complex than the similar known systems.